ATK HP291PM Chevy 350 Mid Dress Engine 325HP

Item #31965 Brand:ATK Engines

Made in the USA
ATK HP291PM Chevy 350 Mid Dress Engine 325HP
ATK HP291PM Chevy 350 Mid Dress Engine 325HP
* ** THIS ITEM IS TEMPORARILY OUT OF STOCK *** FREE SHIPPING on ATK Engines. This item ships directly from the manufacturer and is not available for store pickup. Some engines are made-to-order or can be backordered. Delivery can be delayed up to 5 to 6 weeks but typically ship within 2 weeks.

*Truck Freight Delivery Notice - Driver will only deliver this item to your curb. It is your responsibility to transport the item from curb to your garage.

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ATK HP291PM Chevy 350 Mid Dress Engine, or Stage 2 Engine, is designed for those that may have their own component parts already and who also are interested in completing the finishing touches of the build themselves. A GM Mid Dress engine typically consists of the Stage 1 build out plus the following: Intake Manifold, Distributor, Water Pump, Front Damper & Flex Plate.

Engine Specifications:

  • HP: 330
  • TQ: 380
  • Block: OE block 4 bolt main 1pc seal 1987-2000
  • Bore/Stroke: 4.040 x 3.480
  • Displacement: 350
  • Crankshaft: OE Reground external balance rear of crank/internal balance front of the crank
  • Rods: OE powder metal 5.7”
  • Pistons: Hypereutectic 9.1:1 compression
  • Rings: Moly
  • Camshaft: Hyd. flat tappet
  • Cam Specs: 224/234 @50 .465in/.488ex 112LSA
  • Timing Chain: Double roller
  • Cylinder Heads: Dart cast iron 76cc/165cc 1.94/1.50
  • Rocker Arms: Stamped steel 1.5 ratio
  • Oil Pan: Rear sump 5qt (not for Chevelles with steering behind crossmember, some corvettes and 62-67 chevy II’s)
  • Oil Pump: Melling high volume
  • Balancer: PowerBond internal balance 8” #PB1046-N
  • Flexplate/Flywheel: Pioneer #FRA-159 external balance 168 tooth
  • Intake Manifold: Weiand stealth dual plane #8150
  • Distributor: HEI (Iron gear)
  • Water Pump: OE long pump
  • ATK specializes in muscle. With the highest quality internal parts and Dyno Proven combinations of every engine built, ATK is able to add the most bang for your buck and back it up with an industry leading warranty.

    Don't forget the engine paint!
    Engine Paint


    (1) ATK HP291PM Chevy 350 Mid Dress Engine 325HP


    Engine Information:

    • Oil: Conventional / Non Synthetic 10W30 with Comp Cam zinc additive #159 for first 3000 miles • Oil Filter: Wix or K&N per application • Timing: 34-36 Degrees • Spark Plug Gap: .035” • Firing Order: 18436572 • Octane: 91+ • Stall Converter: 2200-2500 • Exhaust: 1 5/8 Headers • Weight: 430

    Disclaimer: The parts listed are ATK’s recommendations of parts to be used to obtain our power figures listed. Power figures can vary based on parts used by the end user. It is the customer’s responsibility to verify components will work in their application. Some modifications to the vehicle may be required using these and or other aftermarket parts. . ATK reserves the right to substitute parts used in engines if necessary.


    Recommended Components:

    • Carburetor: Quick Fuel 680CFM vacuum secondary’s with electric choke #HR-680
    • Fuel Pump: Holley mechanical 110GPH #12-327-11
    • Spark Plugs: Champion #RV12C
    • Spark Plug Wires: 8mm

    Shipping Instructions and Core Information

    Shipping is free and lift gate will be provided.

    There is no core charge for this engine. You will not be required to send a core back to the manufacturer.

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